As coincidentally came up recently, questions on this site should typically be related to research in mathematics (not questions in mathematics related to research).

A very good answer to a similar question was given by Kaveh, let me quote some key bits:

[Q]uestions have to be stated clearly and in a way which is understandable to mathematicians. Keep in mind that the audience of the site are mathematicians.
It is mainly the job of the person asking the question
to state the question clearly and rigorously in the language of mathematicians.

And:

When

- you have good reasons to believe that a mathematician can answer the question and
that the expertise of a mathematician is required to answer it,
- you have spend time to write a clear question in the language of mathematicians,
- you have written a brief motivation section explaining why you are interested in the question,
- you have demonstrated that you have done your own research and
have tried to answer your question yourself first,

then it is much more likely that your question will get positive feedback on MO[...]

For questions mainly pertaining to historical matters you could consider the site on History of Science and Mathematics instead.